Postoperative tachycardia with focal mechanism.
(A) Electrograms recorded from a number of endocardial sites before
successful focal ablation can be seen. This arrhymthmia was rapid (CL200ms
and regular at the site of successful ablation (right superior pulmonary
vein) in contrast to the irregular but well-formed atrial electrograms
at other sites. This was consistent with second- degree conduction block
between the focus and more distant atrial sites.
(B) termination of the tachycardia 3s after the onset of the onset of
the successful radiofrequency application.
(C) and (D) X-ray images showing the position of the successful radiofrequency
energy application (arrows).

Thomas,S.P.
and others,Mechanism,Localization and Cure of Atrial Arrhythmias Occurring
After a New Intraoperative Endocardial Radiofrequency Ablation Procedure
for Atrial Fibrillation,JACC VOL.35,No.2,2000,Feb.2000;442-50.